Synthetic jewel or bearing material and method of making same



Patented May 4, 1948 SYNTHETIC JEWEL OR BEARING MATERIAL AND METHOD OFMAKING SAME George S. Schaberle, Philadelphia, Pa., assignor, to BendixAviation Corporation, Teterbor N. J a corporation of Delaware NoDrawing. Application November 21, 1944,

Serial No. 564,560 r 1 4 Claims. (on. 106 42) A This invention relatesto synthetic jewel or bearing materials, especially jewel bearingmaterials as used in sensitive instruments and more particularly to asynthetic jewel material or glass as well as the process or method ofmaking the same. I

The present invention has for its objects the provision of a new andnovel jewel bearing material possessing desirable qualities of surfacehardness so as to be wear-resisting and to stand up effectively in usefor long periods; which possesses greater impact strength, toughness,"maximum desirable resiliency, high degree of surface tension, highspecific gravity per mass, and greater work-absorbing power andqualities; as well as a bearing material which is clear and clean, and

fractures cleanly without splintering, being a homogenous meltpossessing no objectionable grit such as is inherent in glasses having ahigh silica content, and is uniformly smooth throughout its mass, beingcapable of economical production in quantities and in all forms for usein the manufacture of such jewel bearings and other articles ofmanufacture.

Hard glass and synthetic jewel materials, spinels, and crystallinestones have been pro- Ammonium aluminum alum 400 Boracic acid 120Magnesium oxide 40 Beryllium oxide or fluoride Zirconium oxide orzirconia 10 Cobalt (metallic) or coloring agent Trace duced for use asbearings, but most of these have j ties, impact strength, toughness, orwere too soft and brittle, had a shattering fracture, were not uniformlysmooth throughout their mass, or contained grit, seeds and stones ordevitrified silica, or when broken or subjected to impact or pressure ofany appreciable degree, would check or splinter thereby destroying theirefiectiveness as a desirable wear-resisting bearing or usefulness as ajewel.

The present invention is designed to overcome the above-relatedobjections and .to provide a jewel bearing material having theadvantages set forth in a remarkable degree, and consists not only inthe composition or mixture, that is, the bearing material per se, butalso in the method or process of making or producing the same, and insuch a manner as to give many advantages and more eflicient results thanwas possible in bearing materials as heretofore composed and made, thusmore efiiciently serving its purpose and providing for a longer life ofusefulness.

In accordance with the invention and to over come the weaknesses ofother well-known compositions and processes for making jewel bearingmaterials, I provide a glass material of the following composition byparts:

I have found that the use of a form of spinel base, consisting ofmagnesium aluminate, and modified by boric anhydride, is best suited toproduce a material composition, having better workabsorbing qualities aswell as greater impact strength than ordinary sodium-silica or othercommercial glasses. Instead of using spinel in the form of a crystallingstone, the latter not being thermoplastic at temperatures to allow it tobe moldedinto small finished articles such as jewel bearings, thematerial of the present invention is prepared synthetically to combinewithmaterials having some of the properties thereof, the other materialshaving desirable physical properties as above alluded to, so that thefinished jewel bearings will possess the qualitiesand physicalproperties best suited for the uses stated without the objectionsreferred to. Therefore, in preparing the material, a batch is made up ofingredients in the proportions by nominal weight as stated, the samebeing then intimately mixed in a suitable way, such as in anelectrically powered mixer or a ball mill, then placed in a suitablevessel or crucible which is placed in a furmace and brought to atemperature of 2750 degrees Fahrenheit, in a time cycle of not less thanone hour and ten minutes. This may be done in any suitable furnaceelectrically or otherwise suitably heated and vented to allow the escapeof the volatile gases. i g

In themolding of jewels or jewel bearings from the synthetic jewelmaterial or spinel glass, it becomes necessary to make quantities of theglass material in excess of the amounts necessary for immediateconsumption by the drop method, that is from molten drops orglobules'from the original melted batch. This is due to the minutequantity consumed by a jewel or hearing and the apparent waste of fuelor power necessary to keep the material at its liquid temperature forlong periods of time, or the alternative of allowing the furnace to cooland spoil the molten batch as well as the possibility of destroying thefurnace lining or crucible. Furthermore, it may become desirable to moldjewels on several machines, some even at a considerable distance awayfrom the material making furnace, possibly insome distant city or state.For this purpose, it is desirable to produce a material which willbetter permit the same to be drawn into cane form and then remelted tobe made into bearings, jewels or other articles instead of being madedirectly into such form from the original molten batch by the drop:method. or otherwise; While the spinal glass formula hereinbefbredescribed may be used to make jewels or bearings by the drop method andcan be drawn into cane or rod form, it does not lend itself as well todrawing; into cane: or rod to be stored for future use; in: thatit has atendency to crystallize or devitrify, as the temperature gradient passesthrough the'lowerlitp'ii dus temperature range. This occurs because theformula or composition above described is at a very critical apex of theatomiolatti'ce-work, and the surface tension accelerator oxides of'beryl lium and zirconium have a tendency to separate out of solution.

In order to circumvent this de-vitrifying stage and to prepare a batchof the synthetic material or glass from which suitable cane maybe drawnfor future use and better serve its purposes efiiciently, two othermetallic oxides are used in place of the oxides of; beryllium andzirconium. These substituted metallic oxides are preferably such aswill. act to give greater elasticity or'fi'ex- ,ibi-lity and. surface:tension or resistivity and abrasive wear to: the material; For this;purpose; the metallic" oxides ct beryllium and. zirconium; are replacedwith oxides of calcium and lead, the latter also known as monoxide orlitharge; in substantially the same or slightly different proportions;as being suitable tor the purposes stated, besides possessing-otherdesirable characteristics. It also been found that theberylliu-m andzirconium salts or oxides are prone to attack the walls. ot therefraetories,,. corrodi-ng them to some extent and. the result is thatthe silica and other components oi the refractory material tend. toenter into the glass batch. This is substantially if not entirelyeliminated by the. substituted. me-

tallic oxides and. fibers drawn from the: material made with thesubstituted metallic oxides. are not only. of. equal. flexibility but.slightly better or greater than. that. obtained with beryllium oxide asdetermined by flexu-re test. Moreover, the abrasive hardness orwork-absorbing; ability and surface. tension. or resistivity to abrasivewear of the material isequal. to orv improved and since the specificgravity is. increased by the use of litharge as compared to beryllium a.closer pack.- mg. of the atomic structure per mass is indicated.

- The method or process. of preparing the material Ammonium alum cs-4'00 Magnesium oxide 40 Borleacid 120 Calcium sulphate or oxideLitharge' (lead oxide ormonoxl'de) Cobalt (metallic? or coloring agentTrace As in the'previ'ous composition or forn'mla, any colorant or decolor'izer such as a trace of cobalt or other metallic coloring agent,maybe added to the batch to give the desired coloring effect orappearance and Without upsetting the boro- 7 specific gravity ofapproximately 2.70 to 2.80,

magnesium-aluminate base and it lends itself Well to large batchmanufacture.

The results from tests prove conclusivel that addition to freedom fromsilica grit which are present in'giass as heretofore produced, thereduction of boric anhydride to below 13 percent of the dehydratedbatch, and with additions of not: over three: percent respectively ofberyllium and; zi'ilconium oxides, the most desirable results areobtained. Boules of such a batch have a and. a; Knoop hardness of 707 to784. At a temperature of about 2732 degrees F.,the batch as thusintimately mixed and heated, melts and goes into a viscous state, and at2750 degrees R, which it is important to attain in one hour and tenminutes, for the measured weight or parts of the materials shown in theforegoing formula, according to experiment andactual practice; themixture goes into a liquid state. It is then preferably allowed to coolslightly into a viscous state to-mold or work into jewel bearings orother articles of commerce; or draw into rod or cane form for latermolding or forming.

The material of the above com-positions may be readily molded orprepared into suitable form economically and with: facility, and insuitable quantities for making jewe'l bearings or other articles ofmanufacture. In such form it breaks clean with a very smooth cleavageWithout checking or splintering.

What I claim and. desire to obtain by Letters Patent 1.. Jewel materialmade from a mixture of the oxides of ammonium aluminum alum of about4200 parts, boric acidZI-ZO' parts, magnesium oxide 40 parts, calciumsulphate 1 0 parts, and litharge 20 parts.

2; J ewel material made from a mixture of'ammom-um alumin in alum 400'parts; boric acid 1-20 parts, magnesimoxide 49- parts; calcium sulphate10 parts, litharge 20 parts and a trace of a metalli c coloring agent.

3. The process of producing a jewel material consisting of intimatelymixing 400 partsammoall-lmimlm alum, parts boric acid, 40 partsmagnesium oxide, 1 0 parts calcium sulphate,.20 parts litharge, andheating the mixture to a. temperatureiof' approximately 2 750? ELinapproximately one hour and. ten; minutes.

4.. The process: of: psoducing a jewel material consisting 0t intimatelymixing doflparts; ammonium. alumimnn alum, 120' parts boric acid; 40parts magnesium oxide; L-O parts calcium oxide, 26 parts: litharge, andheating the mixture to. a temperature of approximately 2750 1 In approximately one: hourand ten minutes.

GEORGE S. SCI-IABERLE;

REFERENQES: CK'EEB The iol-lowing references are of record in the fileof this patent:

UNITED STATES PATENTS.

Number Name Date aoeaoes Berger Augie, 1937 FOREIGN PATENTS NumberCountry Date 442,937 France 1912 OTHER REFERENCES 7 p No. 235,1.08,Ditericks (A. P. 0.), ut. June

